A KILLER flu pandemic could be poised to sweep the globe “tomorrow,” killing as many as 33 million people in its first 200 days.

A catastrophic shift in the flu virus could wipe out 300 million people, a leading flu expert has warned.

The warning comes as vicious outbreaks sweep across the United States and Britain during the northern hemisphere’s winter.

One of these unusually deadly strains first emerged in Australia last year, and has since been dubbed “Aussie Flu”. Officially designated H3N2, this variant has proven resistant to the latest flu vaccine and has become the most common circulating.

It’s also proven particularly deadly to the elderly.

‘Aussie Flu’, along with another strain, ‘Japanese Flu’, are being blamed in a more than 40 per cent surge in flu-related deaths in the US and UK.

Dr Jonathan Quick, chair of the Global Health Council, said the rapidly shapeshifting flu virus is “the most diabolic, hardest-to-control, and fastest-spreading potential viral killer known to humankind.”

Describing what sounds like scenes from a horror film, Quick warned in The Daily Mail of starvation, medicine supplies running low, energy systems crippling under the pressure and the collapse of the global economy.

And what could cause such devastation, on a global scale?

“The most likely culprit will be a new and unprecedentedly deadly mutation of the influenza virus,” he said. “The conditions are right, it could happen tomorrow.”

Flu vaccinations attempt to ‘predict’ the next season’s outbreaks. But the viruses they don’t anticipate can step into the gaps left by those they block. Picture: IstockSource:istock

INEVITABLE TIDE

Flu pandemics happen once in a generation, professor Robert Dingwall, another flu expert, told The Sun Online.

He explained that for a pandemic to happen, there needs to be a “dramatic shift” in the flu virus — something we can expect to see roughly every 20 to 40 years.

The last pandemic hit in 2009-10 when swine flu emerged in Mexico, while the deadly Spanish flu pandemic of 1918 claimed up to 100 million lives — infecting a third of the world’s population.

“A pandemic is when we see a shift, a really radical change that means the population has no real resistance to it.

“It seems that’s what happened in 1918 with Spanish flu and 1956 with Asian flu.”

But while swine flu was classed a pandemic, it wasn’t the “big bang” it could have been.

“It did infect a lot of people,” he told The Sun Online. “But it wasn’t very virulent.”

Quick warned potentially the most dangerous strain of flu is bird flu.

Also known as avian flu, three strains have caused concern in recent years — H5N1, H7N9 and H5N6.

Of those H5N1 poses the greatest threat of mutating and sparking the next killer pandemic, according to Quick.

He said: “If a new and highly contagious strain of H5N1 were to evolve and hitchhike with an unwitting passenger on to an aeroplane, the pandemic situation would quickly assume disaster movie proportions.”

The strain first infected humans in 1997, during an outbreak in Hong Kong.

The bug infected 18 people, killing six after the virus jumped from chickens to humans.

Over the course of 13 years, from 2003 to 2016, the strain has killed 846 people across 16 countries.

A 3D render of a flu virus. Somehow, the flu virus every year picks up and rapidly spreads genetic variations that overcome established immune system - and scientific - defences.Source:Supplied

DEFENCES URGED

Despite his terrifying predictions, Quick said there are measures we can take to ward off the inevitable.

The single most vital thing that must be done is to develop a universal flu vaccine, he said.

A new vaccine being developed by scientists at the University of California, Los Angeles hopes to bring us one step closer to that reality.

The experimental drug was found to protect mice from two different strains in lab tests, it emerged earlier this year.

The aim is for a universal vaccine to replace the yearly jab, which each year is developed based on predictions from the World Health Organisation.

Experts identify the strains most likely to infect people a year ahead of time, meaning unexpected strains can come out of the woodwork and cause chaos.

When it comes to preventing a pandemic, universal vaccine aside, Dingwall warned it can be very difficult, once the bug is out there.

He said: “Flu is very infectious and there is nothing much you can do to stop it moving about the planet.

While flu vaccines may not always anticipate every year’s major strain, they remain the best available defence for the elderly and those with weakened immune-systems. Picture: iStockSource:Supplied

“People tried in 2009 with screening at airports but it doesn’t work because people are infectious for around four days before they get symptoms.

“There is a very limited amount you can do, there’s personal hygiene measures, washing your hands and trying to avoid putting your hands on contaminated surfaces in public then in your mouth.

“But frankly, you’re just as likely to catch it from passing a person in the street who’s sneezed.”

Public Health England has repeatedly plugged its Catch It, Bin It, Kill It campaign, in the wake of the Aussie flu and Japanese flu outbreaks that hit the UK this winter.

Dr. Paul Cosford, medical director and head of health protection at PHE, said last week: “In order to prevent the spread of flu, it is important to practice good respiratory and hand hygiene and to avoid close contact with others who have flu symptoms.”

The latest figures showed flu is still proving a problem across the UK, but that infections have “peaked,” PHE said.